patterson



1366- 21, 1943. l J. E. PATTERSON SAFETY DEVICE FOR HOISTS Filed Aug.12, 1944 Patented Dec. 21 1948 sarcoma I csaaaflsaavwmonflmsrsJunm-Evran rsoam wneeiar'rex.

a clar net/a s thereon.

Ihepresent invention pertains to a novel safety I 1 device fora..J:1qis,t .embodying a hydraulic plunger, such as those used inautocmntheimmir shuns.

The object of the invention-aisqtoaprovidea device to ,preventthahoistfromttalling or slippi from the elevated position'because of leakage ofthe hydraulic system or any other cause. :It-is wvident "Mata-hoist thatus likely to slipnor =fall data .constant hazard to. amam-working-eundermutant. 1

This object is accomplished byzmeansiota leg. or a pair of legs,pivotallysuspended from the platform of me lidlstand-ocoupying avertical position, when the hoist is elevated. Theghpist fib -dr p or iponlytuntn the ats leg rests on the floor. When the hoist is to belowered, the leg is swung upward and into a latch carried by theplatform. This latch embodies a release finger which, on engaging thefloor, releases the leg and places it in readiness to assume thevertical position when the hoist is again elevated. The platform alsocarries another latch adapted to receive and retain the leg in thevertical position so that the leg will not swing when coming intocontact with the floor.

An illustrative embodiment of the invention is disclosed by way ofexample in the following description and in the accompanying drawing inwhich:

Figure 1 is a plan view, partly broken away, of a hoist embodying thepresent invention;

Figure 2 is a cross section taken on the plane indicated by the line 2-2of Figure 1;

Figure 3 is a cross section taken on the plane indicated by the line 33of Figure 2;

Figure 4 is a plan view of the structure shown in Figure 3, and

Figure 5 is a fragmentary plan view, partly in section, illustrating thelatch for holdin the leg in vertical position.

In Figure 1 is shown a hoist or lift including a hydraulic plunger Isurmounted by a head 2 carrying a pair of horizontal rails or channels 3in the usual manner. The rails support at one or both ends a cross shaft4 which is preferably rotatably mounted. On each shaft is mounted a leg5 adapted to swing about the axis of the shaft and which may be securedrigidly to the shaft if the latter is rotatably mounted. If two shafts 4are provided, as in the preferred construction, the legs 5 arediagonally related to each other. The

-ebrresponding latches associated with eachdeg'fs are identical, and'only one set need theneforfe be described in detail.

Each rail 4 carries aiclip including a "downwavdly faoingeoncaveonember6 having .an outwrardly axtending lug l fastened to the basemfthechannel thy bolts}. Themember-fiis positioned to receive theeorrespondinglegiwhenfthe latter is swung to a horizontal position. i Anapertured lug '91s formedupon-the-extension I andis provided with a-hole'Hl alined, with a similarlrole l'llh. thememberfli. In-these holes isislidagbly mounted a lockin pin 12 havingyarounded end "i3-disposed:within the memberfi and-adapted to engage theleg ireceived-therein.Alaterallyextending P 4 4 -is secured to i the base of the lug 8 for apurpose "that-will presently be described. Onone-end---of=the-lockingpin: 12 is mounted a 'washer15 backed-bra cotterpin I6. "Next, to thewasherismounted a disk'fl 'i1aving a laterally a n boss t fidi k normaea against-one side of'thememberfi.

On the pin I4 is rotatably mounted a bell crank lever having a long armI8 extending towards the member 6 and a short arm I9 extending towardsthe disk II. The arm I9 carries a pin 20 rotatably received in the bossI8. The bell crank lever is held on the pin I4 by a cotter pin 2|. Thefree end of the longer arm I8 is formed with an outwardly extendingthreaded stud 22 on which is fastened a trip leg 23 by means of a nut24. The leg 23 has a slot 25 receiving the stud 22 and permitting theleg to .be locked in selected positions to the arm I8.

Another cotter pin 26 is passed through the locking pin I2 in a positionto engage the outer surface of the member 6. Against the pin is a washer21, and between the washer and the member 8, the pin I2 is surrounded bya compressed coil spring 29.

As the hoist is being raised, the leg 5 is free from the clip 6 andreaches a vertical position when the hoist is fully raised. In thisposition it serves as a safety leg or stop to support the hoist in casethe plunger I slips in its cylinder. When the hoist is to be lowered,the leg is lifted and forced into the clip 6 over the rounded end I3 ofthe locking pin I2 and is then held by the pressure of the spring 29 onthe locking pin. As the hoist reaches its lowest position, the tripfinger 23 engages the floor and swings the bell crank lover I8, I9retracting the pin l2 and permitting the leg 5 to fall out of the clipin readiness for the next elevating operation.

Slightly below the shaft 4 and adjacent to the with a notch 31 for apurpose that will presently appear. Adjacent to the notch, the edge ofthe plate 30 is formed with a recess 38 adapted to receive the leg whenin the vertical position. The

leg is formed with a rib 39 that snaps into the '2 notch 31. Thus, theleg remains locked in the vertical position when it takes the weight ofthe hoist. Before swinging the leg into the clip 6, as previously setforth, the finger 33 is obviously swung away from the rib 39 by pressureon the unnotched end thereof. Adjacent to the finger, the plate 30 isformed with a lug 40 to limit the movement of the finger under theaction of the spring 36.

While a. specific embodiment of the invention has been shown and beendescribed, it will be understood that variousalterations may be madewithout departure from the spirit of the invention as indicated by theappended claims.

WhatI claim is:

.1. In a hoist having a platform, a leg having its upper end pivotallyattached thereto on a horizontal axis and adapted to swing by gravity toa vertical position, a bracket attached to said platform at a pointthereon spaced from said axis and having a flange engaging said leg tolimit upward pivotal movement thereof, a latch member movably mounted onsaid bracket, a spring arranged to move said latch member intoengagementwith said leg to hold said leg in locked position adjacentsaid bracket, a pivotally mounted bell crank lever arranged to move saidlatch member,

and a finger carried by said bell crank lever and extending below saidplatform for engagement with the ground to retract said latch memberwhen the platform is lowered.

2. In a hoist having a platform, a leg having its upper end pivotallyattached thereto on a horizontal axis and adapted to swing by gravity toa vertical position, a bracket attached to said platform at a pointthereon spaced from said axis and having a flange engaging said leg tolimit upward pivotal movement thereof, said bracket having a secondflange spaced from said first mentioned flange and said flanges beingprovided with aligned openings therein, a latch member slidably mountedin said openings, a spring arranged to move said latch member intoengagement with said leg to hold said leg in locked position adjacentsaid bracket, a bell crank lever pivotally mounted on the secondmentioned flange of said bracket and having one leg engageable with saidlatch member, and a finger extending downwardly from the other leg ofsaid bell crank lever and below said platform for engagement with theground to retract said latch member when the platform is lowered.

- JULIAN E. PATTERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNI [TED STATES PATENTS Australia May 23, 1939

